Rheostat and the like



E. R. STOEKLE RHEOSIAT AND THE LIKE July 10, 1923- Filed July 51. 1922 Patented July 10, 1923.

' UNITED STATES PATENT OFFICE.

ERWIN R. STOEKLE, or MILWAUKEE, Wisconsin.

RHEOSTAT AND THE LIKE.

Application filed July 31,

and regulation of small currents such as ocour in radio apparatus and instrument regulation.

An object is to provide a rheostat structure that will hold a helically wound resistor element firmly in place in a groove at the cir umference of acylindrical structure.

Another object is to'provide a structure in which the groove for retaining the resistor element is formed by the assembly of moulded or punched circular disks.

Another object is to provide an improved rheostat structure in which the resistor is retained between circumferentially grooved metal disks electrically insulated therefrom,

whereby efi'ective cooling of the resistor is obtained by thermal condu tion to and radiation from the metal disks.

' Another object is to provide an improved rheostat in which both coarse. and fine adjustment of the resistance may be obtained by means of a single operating knob, the device for accomplishing fine adjustment being a simple attachment to the plain rheostat.

Another object of this invention is to provide an improved rheostat in which both fine and coarse adjustments of the resistance may be independentlyaccomplished and independently indicated at the operating knobs or handles. i

The novel features and improved structure of this rheostat are made clear by the following description and the drawings of Figs. 1 to 4.

Figure 1 shows in cross section a preferred form of the simple rheostat. Fig. 1 shows a somewhat simplified disk assembly and method of holding the resistor in place.

Figure 2 is a rear View of the simple 1922. Serial No. 578,823.

rheostat showing the contact arm and binding posts in relation to the resistor.

Figure 2 is a perspective View of the plain rheostat of Figs. land 2 with a simple attachment for accomplishing fine adjustment of the resistance, by means of a single knob.

Figure 3 is a perspective view of the rheostat with simple modificationsto accomplish fine adjustment of the resistance and to independently indicate the fine and coarse adjustments.

Figure 4 is a cross section of the rheostat shown in Fig. 3.

Referring to the Fig. 1 the helically wound resistor 1 is shown retained in a groove formed by the superposition of the disks 2, 3, 4t, 5 and 6. are prefe ably-of sheet metal with their edges turned slightly inward. The disks 3 and 5 are of insulating material such as paper or thin fibre, and the disk 4 s likewise of insulating material su h as fib e.

The assembly of these disks with the resistor is accomplished as follows: The disks 4:, 5 and (5 are assembled over the hollow rivet or grommet 7, and the resistor 1 which may be in the form of a long helical spring,

is stretched around the disk 1. The disks 2 and 3 are then superposed and the whole firmly compressed by turning over the edges of the grommet 7.

Figure 1 shows another method of assembling the resistor between the disks and eliminates the center disk 4. In this construction it is necessary to press circular grooves 23 and 24 near the edges of the disks 61 and'62. These disks are held in compression by the bushing 25, and the pressure exerted by the disks upon the helical resistor 26 serves to hold the turns of the resistor in circumferential and radial alignment. Thin insulating discs 63 and 6 insulate the resistor 26 from discs61'and 62.

Referring again to Fig. 1 the shaft 8 extends rotatably through the grommet 7 and the panel 9 upon which therheostat is mounted. The front end of this shaft has fastened to it the pointer 10 and the oper-' ating knob 11.. The contact arm 12 is fastened as shown to the collar 13 which is adjustably fixed to shaft 8 by means of a set screw 14:.

The outside disks 2 and 6 The binding post 15 is fastened to the insulating disk 4 by means of the screw 17 and is electrically connected to one end of the resistor element. The binding post 18 (Fig. 2) is fastened to the metal disk 2 as well as the insulating disk 4 by means of the screw 19. A spring Washer 20 serves to make good electrical connection between the disk 2 and the contact arm 12.

The current therefore enters at binding post 15, passes through the resistor to the point where the latter is in contact with the arm 12, thence through the spring washer 20 to the metaldisk 2 and binding post 18. The holes 21 and 22 are for the mounting screws, that fasten the rheostat to the panel.

Figure 2 shows the rheostat with a simple attachment for obtaining very fine and gradual adjustment of the resistance. In this figure an insulating sector 27 is fastened to the hub 28 which is rotatable on the shaft29. This sector carries the contact arm 30 which bears on the resistor 65, and also carries a slide wire 31 one end of which is fastened to the pin 32, and the other end of which is electrically connected to the arm 30. The contact arm 33 which is fixed to the rotatable shaft 29 bears upon the slide wire as shown.

The current enters at the binding post 34, passes through the resistor 65 to the contact arm '30, thence through the slide wire 31 to the contact arm 33. From this contact arm the current passes through the shaft themain resistor and thus vary the resistance insteps equal to the resistance of any one turn of the main resistor.

In order to obtain infinitesimal variations of the resistance at any value thereof, it is only necessary to have the total resistance in the slide wire 31 equal to or greater than the resistance of one turn of the main resistor.

It is thus apparent that infinitesimal variations of the resistance can be accomplished by the use of only a single operating knob.

It is obviously feasible to fasten the sector 27 to a tubular shaft extending through the rheostat and carrying a pointer at its exterior end, whereby the position of the contact shoe 30 upon the main resistor can be indicated at the front of the mounting panel. Figures 3 and 4 show the rheostat with attachments for obtaining very fine and gradual variations of the current by means of two operating knobs. The main resistor structure in these figures is the same as that shown in Figs. 1, 2 and 2*.

Referring to the Fig. 4 a tubular shaft 38 extending rotatably through the mounting panel 59, and the grommet 58 has fastened to it by means of the collar 39 and set screw 40 an insulating disk 41, in the edge of which is cut a circumferential groove retaining a slide wire 42. The contact arm 43 bears upon this slide wire and is fastened to the shaft 44 by means of a collar 45 and set screw 46. The shaft 44 extends rotatably through the tubular shaft 38 and its operating knob 47, and at its exterior end has fastened to it the operating knob 48.

The contact shoe 49 is fastened to the disk 41 and electrically connected to one end of the'slide wire 42, the other end of the slide wire 42 is fastened to the insulating disk by means of a pin 50.

Referring to Fig. 3 the current enters at the binding post 51, passes through theresistor to the contact shoe 49, thence through the slide wire 42 to the contact shoe 43. From 43 the current passes through the shafts 44 and 38 and the spring washer 52 to the metal disk 57 and the binding post 53. The spring 54 serves to hold theknob 48' againstthe knob 47 and also to make better contact between the hub 45. and the shaft 38.

It is apparent from the above description and from the Fig. 3 that a movement of the contact 49 towards the binding post 51 decreases the resistance in steps ,equal to the resistance of one turn of the main resistor.

It is further apparent that the movement of the contact arm 43 towards 49 decreases the resistance in infinitesimal steps thus allowing of very fine and gradual adjustment of the resistance between the binding posts 51 and 53.

Referring again to the Fig. 4, the pointer 55 is threaded to the shaft 38 and serves to indicate in conjunction with a scale marked on the panel 59, the position of the contact shoe 49 upon the resistor 60. The pointer 56 is screwed on to the shaft 44 and serves to indicate in conjunction with a scale on the knob 47 the position of the contact shoe 43 upon the slide wire 42. It is therefore possible to independently and accurately indicate by this arrangement, the

magnitude of the resistance in the main resistor and in the slide wire.

What I claim is new and desire to secure by Letters Patent is:

1. A rheostat comprising a helically wound resistor whose axis lies in a circumferential groove formed by the co-axial superposition of a lurality of circular disks.

2. regulable rheostat comprising a heliluu . cally wound resistor whose turns are axially retained in a groove formed by the co-axial superposition of a plurality of circular disks; a contact arm bearing on the turns of said resistor and fastened to a shaft rotatably extending through a central tubular rivet, said rivet holding said disks in 10mpression, and exerting a pressure upoi. the resistor, whereby its turns are held ll: lateral and circumferential alignment in said groove.

3. A rheostat comprising a resistor a;-.ially retained in a circumferential groove fc rmed by the *co-axial superposition of two metal disks near whose edges are pressed circumferential grooves, means for insulating the turns of said resistor from said metal disks, and means for compressing said disks where.- by the turns of said resistor shall be firmly held in said groove.

4. A rheostat comprising a resistor axially retained in a circumferential groove formed by the co-axial superposition of two metal disks near whose edges are pressed circumferential grooves, means for insulating the turns of said resistor from said metal disks, and means for compressing said disks whereby the turns of said resistor shall be firmly held in said groove, said resistor having its outer edge exposed for the purpose of making contact with a contact s 0e.

5. A rheostat comprising a helically wound resistor axially retained in a circumferential groove formed by the co-axial' superposition of a plurality of disks; namely, two outside metal disks with their edges turned over a portion of the outer part of said resistor thin disks of paper or the like for insulating said resistor from said metal disks; 9. central insulating disk of smaller diameter than said outside disks for holding said resistor in axial alignment with respect to said disks,

and for supporting two binding posts; a tubular rivet for holding said disks in compression, and through which extends a rotatable shaft carrying a contact arm which makes contact'with the turns of said resistor.

6. A rheostat comprising a helically wound resistor axially retained in a circumferential groove formed by the co-axial superposition of a plurality of disks, the two outside disks being of metal, said metal disks being electrically connected to a rotatable contact arm bearing on the turns of said resistor, and to a binding post; a second binding-post insulated from said metal disks and electrically connected to one endpof the wire of said resistor.

7. Aregulable rheostat comprising a circularly disposed main resistor,'a co-axially rotatable insulating member, said member carrying a contact arm bearing on the turns of said resistor; a slide wire mounted on said member and having one of its" ends electrically connected to said contact arm; a second rotatable contact arm bearing upon said slide wire, and movable thereon between stops at the ends of said slide wire, said stops serving as a means of rotating said sector and its associated contact arm by the rotation of said second contact arm. I

8. A rheostat comprising a helically wound resistor axially retained in a circumferential groove formed by the co-axial superposition of a plurality of circular disks; a rotatable tubular shaft'extending co-axially through said disks and carrying a circular insulating disk on the edge of which is a circumferential groove retaining aslide wire; a contact arm fixed to said insulating disk and electrically connected to one end of said slide Wire, said contact arm bearing on the turns of said resistor; a sec- 0nd contact arm bearing on said slide wire, and fastened to a shaft extending through said first mentioned tubular shaft.

9. A rheostat comprising a resistor axially retained in a circumferential groove formed by the co-axial superposition of a plurality of circular disks, a co-axially rotatable insulating disk carrying a contact arm bearing on the turns of said resistor; a slide wire laid ina circumferential groove in said disk, one end being connected to the said contact arm, the other end being suitably secured to said disk; a second contact arm bearing on said slide Wire and mounted on a rotatable shaft, through which it is electrically connected to two outside metallic disks enclosing the main resistor; two bindin posts, one of which is electrically connecte tosaid metal disks the other of which is'insulated therefrom and connected to one end of the wire of said resistor.

10. A rheostat comprising a circularly disposed resistor,-an insulatin disk carrying a contact arm .bearing on the turns of said resistor and fixed to a rotatable tubular shaft the exterior end of which has fastened to it an operating knob and a pointer for indicating the position of said contact arm with respect to said resistor; a slide wire laid in a-circumferential groove in the said insulating disk, one end being connected to the said contact arm the other end being suitably secured to the disk; a second contact arm bearing on said slide wire and mounted on a rotatable shaft extending through said tubular shaft and its operating knob; an operating knob and apointer fastened to said shaft for the purpose of indicatin upon a scale marked upon said first mentioned knob the position of said second said slide wire.

In witness whereof I scribed my name.

. ERWIN Rl STOEKLE.

have hereunto subcontact arm upon 

